EVALUATION AND CHARACTERISATION OF BACTERIAL ENDOPHYTES FOR SOME FUNCTIONAL ATTRIBUTES
The study was designed for the evaluation and characterisation of some endophytic bacteria.The colonization of the internal tissues of the plant by the bacterial endophytes is known to promote plant growth and health. This study aims to explore the potential of some bacterial endophytes as a viable source of antimicrobial compounds as well as to facilitate a better understanding of their plant growth promotion activities. Besides, they were also investigated for their ability to produce extracellular enzymes. In the present study, 18 bacterial isolates were characterised morphologically and microscopically into Gram positive and Gram negative rods and cocci. This was followed by the biochemical characterisation which revealed the potential of 13 bacterial cultures for glucose utilisation, 10 for nitrate reduction, 6 for citrate utilisation and 5 for mannitol reduction. All the isolates presented extracellular enzymatic activities which were ranked as follows: lipolytic (72.2%), proteolytic (66.6%), amylolytic (38.8 %), cellulolytic (33.3%) and pectinolytic (27.8%). However, phosphate solubilisation and chitinase activity was not detected among the isolates. The endophytic isolates also exhibited good potential for plant growth promotion by producing Indole-3-acetic acid (33.3%) and siderophore (83.3%). HCN production was observed in all the strains. The crude extracts of bacterial endophytes revealed a considerable biocontrol potential against a panel of bacterial pathogens demonstrating a broad spectrum of activity against Klebsiella and Enterococcus faecalis. However 75% of the extracts were capable of inhibiting Bacillus cereus, Escherichia coli and Staphylococcus aureus. Least activity was recorded against Pseudomonas alcaligenes. Thus, the biocontrol and plant growth promotion attributes of the endophytic isolates examined through Indole acetic acid, siderophore and HCN production suggests their implicative role in plant growth, development and health.
Keywords: Endophytes, biochemical characterisation, biocontrol agents, plant growth promotion